I, too, was considering trying to add the illuminated door scuff plates, but I just looked inside my wiring trough, underneath where the existing non-illuminated scuff plate is, and I see NO connectors tucked in there, which was surprising. However, in thinking about it, my XLT did not come with any "ambient lighting", so perhaps the wiring harness for the more basic Explorer deletes those connectors needed for the illuminated scuff plates? While that seems strange of Ford, to want to manufacture and stock at least two different wiring harnesses like that (to delete any extra connectors), who knows what lack-of-hindsight actions their designers might have taken? Seems to me that a single, "universal" harness for all that model year would make life easier on them overall.
BTW, Ford DOES make an add-on multi-color ambient lighting kit, in which you mount a couple of LED modules underneath each side of the footwells, as well as additional LED's for the console, cupholders, and forward storage pocket areas. Because I didn't like having nothing but darkness in the floor areas when driving at night, I ordered and installed one of these kits, putting the on-off & color-selection switch inside my console's storage compartment. It works well, and provides the light needed to visually enhance the floorboard areas for night driving.
I do not believe, however, that there is any way to retrofit and connect a pair of the optional illuminated scuff plates into this optional kit. Too bad!